 Much of the criticism of Linux is related to the lack of desktop and laptop adoption, although as of 2015 there has been growing unease with the project's perspective on security and its adoption of systemd has been controversial.Some security professionals say that the rise in prominence of operating system-level virtualization using Linux has raised the profile of attacks against the kernel, and that Linus Torvalds is reticent to add mitigations against kernel-level attacks in official releases.Linux 4.12, released in 2017, enabled KASLR by default, but its effectiveness is debated.